Rheostat.



A. J. ASCH.

RHEOSTAT.

APPLICATlON FILED FEB. 12, 1916.

Patented June 13, 1916.

A TTORIVEVS Parana? OFFICE.

ANDREW" J. ABC-E, 91? NEW 'YOEK, Y.

Specification. of Letters Iatent.

Patented June 53.3, 1916.

Application filed February 1E3, 193%. Serial No. 77,329.

To all whom it may concern Be it known that L-ANDREW J. Asor-r, acitizen oi the United States, and a resident of the-cityoi New York,borough of Man- 'hattan,,inthe county and State of New Yorkyhaveinvented a new and Improved ltheostat, of which the following is a full,clear, and exact description.

This invention relates to rheostats especially adapted for treatments bythe cataphoresis and ionization methods, although the invention is notnecessarily limited to this use. i

The invention has for its general objects to improve the constructionand operation of rheostats so as to be reliable and efiicient in use,comparatively simple and inexpensive tomanufacture, and so designed asto enable very line adjustments for small variations in current strengthA more specific object of the invention is the provision of arheostat ofthe coil type in which a contact slider makes contact with theconvolutions of the coil to thereby vary the effective length of theresistance of the circuit, the movement of the slider being; effected bya micrometer screw from which. the slider can be disengaged wheneverdesired, for effecting a quick adjustment or the bringing of the sliderback to its initial position.

With such objects in view, and otherswhich'will appear as thedescription proceeds, the invention comprises various novel features ofconstruction and, arrangement 'of parts which will be set forth withpar;

ticularity in the following description and claims appended hereto.

In the accompanying drawing, which illustrates one embodiment of theinvention and wherein similar characters of reference indicatecorresponding parts in all the views, Figure 1 is an elevation of thedevice; Fig. 2 is a rear view; Fig. 3 is a trans verse section on theline 33, Fig. 2"; and Fig. 4 is a detail view of the slider.

Referring to the drawing, A designates the c'asing of the rheostat whichcomprises a three-sided shell 1 open at both ends and at one side, andin the ends are disposed blocks 2 of insulation which are secured. tothe shell by screws or equivalent fasteners 3. Ii the device is to beapplied to a panel, bolts 4 are anchored in or fastened to the endblocks 2. Each end blocl: has an ing 5 ior holding a brass or othernoneaia g 'ing upwardly on the casing, and on this stem is a knobcontacts to any (loss netic tube which. forms the support for theresistance coil or helical Winding'i', there being mica interposedbetween the core or support 6 and the winding. The

coil is made of very nne wirewith a film g oi enamel coating, so thatthe wire can be wound with its convolutions close together to insure alength of resistance wire within a small compass. The terininalsfi andi0 the coil are connected by screws ii and 332, to the blocks 52, andthese screws are grounded on adjacent bolts ii-to which circuit Wiresare to be connected.-

To vary the effective length of the resistance coil a movable contact isemployed to move in engagement with the successive convolutions. Thiscontact device coinprises a slider B which is a block having openings 13and let through which extends fixed guide red 15 a rotary screw it, bothif "hich are mounted in the end blocks 52 the casing. 0n the sliderarespring; contact members 1? which. bear against the coil, theinsulation of which is removed at fulcrumed on the guide rod 15, andthis ic ver has an opening it) which is threaded so as to mesh with thethreads of the screw, engagement of the threads of the lever with thescrew being maintained by a spring 20 fastened to the body of the sliderand press the lever, as shown an Fig. 3. The lever has a stem orshanloll extending out of a longitudinal slot whereby the lever can bedepressed't laterally to shift the red point on the coil. The screw 16is employed for effecting: a very fine adjustment oi the slider andthere by enable nice variations oi current strength to be obtained, thescrew being turned by means oi. a knurled knob or equivalent means 34fastened. to the screw at one end. The guide rod 15 has one endconnected by a wire 25 with one of the bolts 4, so that the slider :anbe connected with the electric circuit. Thus, in operation, either oneof the ends of the coil is connected with one side of the circuit andthe slider with the other side, and by adjusting the position of theslider through the turnirc: oi the screw, any desired an'munt c i be cutinto or out of if. c

l1S-- engage it from the screw, and 'henfwhile h'eld depressed, moved itltd .with the 'the best embodiment thereof, I desire to have From theforegoing description taken in connection with the accompanying drawing,the advantages of the construction and method of operation will bereadily understood by those skilled in the art to which the inventionappertains, and while I havedescribed the principle of operation,together device which I now consider to be it understood that the deviceshown is merely illustrative and that such changes may be made whendesired as fall within the scope of the appended claims.

aving thus described my invention, I claim as new and desire to secureby Letters Patent:

1. A rheostat comprising a casing, a resistance coil mounted therein, aguide rod in the casing extending longitudinally along the coil, a screwrotatably mounted in the casing and disposed parallel with the guide'rod, a slider movable along the rod, contact means on the slider forengaging the con volutions of the coil, a movable element mounted on theslider and having threads for engaging the screw whereby the rotation ofthe latter moves the slider, means for yieldingly holding the element inengage ment with the screw, said element having a portion extending outof the casing for permitting the operator to release it from ,the screwand effecting a quick adjustment of the slider, and. means forconnecting the slider and a terminal of the coil to an electric circuit. r

2. Arheostat comprising a casing formed of a shell having an open sideand open ends,

blocks of insulation fastened in the ends, a n0nmagnctic tube fastened.in the blocks, in helical resistance coil carried by the tube, a slidermovable along the tube, a support carrying the slider, contact means onthe slider for engaging the convolutions of the coil, an operating screwrotatably mounted in the end blocks, means for turning the screw, andmeans on the slider for en aging the screw to cause the slider to movehythe rotation of the screw.

3. A rheostat comprising a casing formed of a shell having an open sideand open ends, blocks of insulation fastened in the ends, a.non-magnetic tube fastened in the blocks, a helical resistance coilcarried by the tube, a slider movable along the tube, a support carryingthe 'slider, contact means on the slider for engaging the convolutionsofthe coil, an operating screw rotatably mounted in the end blocks,means for turning the screw, a lever operati'vely connected with theslider and having threads normally engaging the scrcw, and a spring onthe slider and pressing on the lever for maintaining it in engagementwith the screw, said casing having a slot through which the leverextends for enabling the operator to release the lever and move thesame, together with the slider, independently of the screw.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

ANDREW J. ASCII.

Witnesses:

ALFR D A. KoHN, lViLLmM KAUFMAN.

